This study is examining trends in the amount and composition of capital investment by voluntary short-term general hospitals in Massachusetts over the period 1967-76 and is attempting to determine the impact of the Commonwealth's Certificate of Need (CON) Program on this investment. The methodology employed combines an analysis of detailed information on capital investment by a random sample of hospitals stratified by teaching status and location with a case-study examination of selected capital projects from the "pre-CON" period 1967 -71, the "early CON" period 1972 - 73, and the "mature CON" period 1976 -77. Preliminary analysis inicates that the rate of increase in "assets/bed" compared with that of "number of beds" was already greater prior to the introduction of CON, suggesting that investment in "intensity/bed" rather than in increased numbers of beds is not a phenomenon attributable solely to the presence of CON regulation. Among teaching hospitals, the rate of increase in number of beds was not significantly different following the introduction of CON, but both "plant expenditures/bed" and "major movable equipment expenditures/bed" were significantly higher. Among non-teaching hospitals, the rate of increase in number of beds during 1972-76 was lower than before CON although the difference is not statistically significant; the level of "plant expenditures/bed" and "major movable equipment expenditures/bed" remained virtually constant during the two periods. Explanations for these observations are being pursued.